Dietary niche dynamics of breeding seabirds in coastal Newfoundland under shifting prey availability: A stable isotope-based approach
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Date
2018-12-21
Authors
Jenkins, Edward
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Abstract
On the Newfoundland coast, an annual pulse of the capelin (Mallotus villosus), provides an excellent opportunity to investigate the influence of varying prey availability on seabird diet. We investigated seabird species- and assemblage-level dietary responses to shifting capelin availability of three breeding auk species (Atlantic puffin Fratercula arctica, razorbill Alca torda, common murre Uria aalge), and Leach’s storm-petrel (Oceanodroma leucorhoa) using stable isotope ratios (δ15N, δ13C). At the species level, trophic position increased, and dietary niche breadth narrowed for auks. We also conducted a controlled feeding experiment on captive adult puffins and murres to calculate diet-tissue discrimination factors (DTDFs), specifically two blood components (i.e., plasma, cellular component). After applying these DTDFs to wild birds, Bayesian mixing model results supported our other study. Using published DTDFs from other studies resulted in different prey proportions, reiterating the importance of species- and tissue-specific diet-tissue discrimination factors when reconstructing dietary proportions of wild seabirds.
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Keywords
Stable isotopes, Seabirds, Newfoundland